Transducer



Sept. 21, 1954 c. JENSEN 2,689,885

TRANSDUCER Filed April 11, 1950 125 E10. CZarencel i n J00 J00 BY M; W MI .trical equipment including amplifiers.

Patented Sept. 21, 1954 TRANSDUCER Clarence F. Jensen, Racine, Wis., assignor to Webster Electric Company, Racine, Wis., a corporation of Delaware Application April 11, 1950, Serial No. 155,177

Claims.

The present invention relates to transducers and particularly to transducers used in the reproduction of sound from records of various sorts and which are often called pick-ups or pick-up units and include a pick-up cartridge.

At the present time pick-ups and pick-up cartridges are designed for use with associated elec- Some of this equipment requires a low voltage input and in this event the cartridge is designed with the requisite output voltage and output voltage characteristic. Other equipment requires a high voltage input and in this event the cartridge again must be designed accordingly. The result is that different cartridge constructions are required. This is disadvantageous even during initial manufacture of pick-ups for use with particular apparatus, but is even more disadvantageous in the case of repair and replacement sales.

One of the objects of the present invention is .first, a suitable electro-mechanical transducer element which may be a piezoelectric crystal, and second, impedance means adapted selectively to be connected to the transducer element to change its output. For example, the transducer element may itself have high voltage and high impedance output characteristics enabling it to be used with associated apparatus designed for these characteristics. The impedance device which may be a capacitor is also mounted within the housing and is adapted to be connected to the output of the crystal so as to provide a lower output voltage. The desired output characteristic may be obtained in a simple manner through the use of terminals extending outside the housing and connected to both the transducer element and impedance device and a terminal clip adapted to be secured to selected terminals for the purpose of changing the characteristics.

Other objects and advantages of the present invention will become apparent from the ensuing description of an illustrative embodiment thereof, in the course of which reference is had to the accompanying drawing, in which:

(Cl. I'm-100.41)

Fig. 1 is a longitudinal horizontal cross sectional view through a pick-up constructed in accordance with the present invention;

Fig. 2 is a longitudinal vertical cross sectional view through the pick-up;

Fig. 3 is a diagrammatic circuit illustrating the electrical connections of the transducer element and capacitor to the terminals;

Figs. 4 to 6 are fragmentary views illustrating different types of output connections for high voltage and high impedance characteristics;

Figs. '7 to 9 are similar views illustrating output connections for lower voltage output;

Fig. 10 is a plan view of a terminal or connector clip that is utilized in the lower output voltage connections; and

Fig. 11 is an elevational view of the clip.

Referring now to the drawings, it may be noted that the pick-up or pick-up cartridge is indicated generally by the reference character Ill. It comprises a housing 12 including alike but opposed portions [4 and [6 adapted to be secured together in suitable manner by the rivets l8. The housing portions can be stamped from metal. or

' molded from some suitable plastic material.

The pick-up illustrated is of the single needle t pe including the single needle 20, although it should be understood that the present invention is applicable to other types of pick-ups and including more than one needle. The needle 29 is suitably secured in a needle chuck 22 extending outside of the housing through a suitable aperture 24. The chuck is formed as an integral part of a coupling element 26 including spaced trunnions 28 and 30' compressively held in bearings 32 and 34 that are held under compression by complementary portions of the housing sections l4 and [6. A needle holding screw 36 extends outside of the housing where it is readily accessible to release the needle when desired. If desired the holding screw 36 may be used as the front trunnion, as disclosed and claimed in my copending application Serial No. 97,824 filed June 8, 1949, and assigned to the assignee of this application.

A suitable electro-mechanical transducer element 40, which is illustrated as being of the "twister piezoelectric crystal type, but which may be of other types, is mounted within the housing between the damping and holding plugs '42, held between the opposed walls of the housing, for actuation by the needle 2i! and the coupling element 26,. the latter being provided with spaced clamping jaws 44 at one end adapted to embrace and to be secured to the transducer element 40. A damping or clamping strip 46 can be placed between the jaws and crystal. Further detailed description of the pick-up cartridge is not believed to be necessary in view of the fact that it is of conventional construction and it has been illustrated and described thus far only to provide a better understanding of the present invention.

Theoutput terminals of the transducer element 40 are connected to the pick-up terminals 56 and 52 through conductors 54 and t, respectively, which are insulated from the housing by insulator tubes 58, also located between the housing walls. The terminals are mounted upon a terminal plate 66 which is made of some suitable insulating material, such as Bakelite. The terminal 52 is connected by a ground strip 62 to the housing, if the latter be of metal, as is preferred, thereby effectively making the terminal 52 a ground terminal.

In accordance with the present invention, the transducer element, which in and of itself provides desired high voltage, high impedance output characteristics, has associated with it an impedance device kit, also mounted within the housing for reducing the. output voltage. The impedance device reduces the output impedance somewhat but not enough to change it, for example, from a high impedance output device to a low impedance one. The impedance device 64 may take the form of a small capacitor which is mounted within the housing above the tubular insulators 58 so that it is held thereaga-inst by a wall of the upper housing section 62. One terminal of the capacitor is connected by conductor 65 directly to terminal Eli and the other terminal is connected by conductor $8 to a third terminal Hi which is also mounted on the terminal plate 68. The conductors E56 and 58- are insulated by the smaller tubular sleeves 82.

The electrical connections are partly illustrated in somewhat diagrammatic form in Fig. 3. From this it may be readily noted that the capacitor 54 is connected across terminals '50 and it while the transducer element 4b is connected across terminals hi) and 52. The ground strip 52 is connected to terminal 52.

The pick-up of the present invention can be utilized readily with apparatus requiring either a high or low input voltage. Various connections for the former are illustrated in Figs. 4 and 6 and various connections for the latter are illustrated in Figs. 7 to 9.

The high voltage connections can be made with various types or" output conductors. In Fig. 4 there is illustrated a two conductor output. The two conductors are indicated by reference characters i4 and "it, each. having a terminal is attached to it for suitable fastening to the terminals 56 and 52. When this type of connection is used, the ground strip 82 is cut to disconnect terminal 52 from ground.

In Fig. 5 there is illustrated a high voltagev connection utilizing a single shielded conductor. In this case the conductor Bi l is adapted to be connected to terminal 56 and the shield 82 is adapted to be connected by conductor 3 to the terminal 52.

In Fig. 6 there is illustrated a two conductor shielded type of output. The two conductors 86 and 88 are adapted to be connected to terminals 5i! and 52, while the shield 99 is adapted to be connected by conductor a2 and terminal 94 to the pick-up housing or other grounded element. In this case the ground strip 52 is again out to disconnect terminal 52 from ground. 7

In order to convert the high voltage output to a low voltage output, the terminals 52 and Ill are connected together by what may be called a terminal pin receptacle which is illustrated in Figs. 10 and 11 and indicated as a whole by reference character 96. It is somewhat triangular in form and is provided with opposed notches 98 at its apex in order to facilitate bending thereof properly to locate the generally circular terminal pin encircling portions we at its ends. It is apparent from Fig. 11 that the pin or terminal circuit portions liiil can readily be slipped over and frictionally or otherwise secured to the terminals 52 and 10, thereby effectively to connect the capacitor 64 in parallel with the crystal and provide the desired low voltage, low impedance output across terminal 50 and the now connected terminals 52 and '10. The notches 98 also facilitate breaking of the receptacle 96 into two parts, which parts can be used as two of the terminals 18.

In Fig. 7 there is-ill'ustrated the two conductor output. Conductor It is adapted to be connected as heretofore to terminal at but conductor it is connected to the now connected terminals 52 and it, as by connection to the pin receptacle 98.

In Fig. 8 there is illustrated the shielded single conductor connection. The conductor fit, as heretofore, is adapted to be connected to terminal 53, while the shield conductor 82 is connected by conductor M to the receptacle 9%.

The shielded two conductor output connections are illustrated in Fig. 9. Here conductor $5 is again illustrated as adapted to be connected to terminal 53, while conductor 38 is connected to the pin receptacle 96.

From the foregoing detailed description of the present invention, it may be noted that it provides a transducer or pick-up which can readily be used with new or existing apparatus as initial or replacement equipment. It is readily transformable to provide different outputs, such as high and low voltages.

While the present invention has been described in connection with details of an illustrative em: bodiment, it should be understood that these details are not intended to be limitative oi the invention except as hereinafter set forth in the claims.

Having thus described my invention, what I claim as new and desire to secure by United States Letters Patent is:

i. A variable output transducer assembly comprising a housing, a transducer element mounted within said housing, said element being of the type having an equivalent capacitance in parallel therewith, capacitive means mounted within said housing for varying the output level oi said element, first terminal means carried by said housing and connected to both said element and said. capacitive means, second tenninal means connected only to said transducer element, and third terminal means connected only to said capacitive means, said second and third terminal means being connectabie together to reduce the output voltage of said element.

2. A variable output transducer assembly comprising a housing; a transducer element mounted within said housing; impedance means mounted within said housing for varying the output level of said element; first terminal means mounted on said housing and connected to both said impedance means and, said transducer element; second terminal means mounted on said housing and connected onlyto said transducer element; third terminal means mounted on said housing and connected only to said impedance means; said first, second and third terminal means extending outwardly from said housing; and a connector adapted to be mounted on said second and third terminal means externally of the housing to electrically interconnect the impedance means with the transducing means whereby the output level of said element is varied.

3. A transducer including a housing, a transducer element mounted within said housing, output level changing impedance means for said transducer mounted within said housing, a first terminal mounted on said housing and connected to both said impedance means and transducer element, a second terminal connected only to said transducer element, and a third terminal connected only to said impedance means.

4. A transducer including a housing, a transducer element mounted within said housing, output level changing impedance means for said transducer mounted within said housing, a first terminal mounted on said housing and connected to both said impedance means and transducer element, a second terminal connected only to said transducer element, a third terminal con- References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,027,494 McMeen May 28, 1912 1,356,634 Koch Oct. 20, 1920 1,613,851 Sengebusch Jan. 11, 1927 1,778,207 Anderson Oct. 14, 1930 1,835,073 McCatchie Dec. 8, 1931 1,868,960 Anderson July 26, 1932 2,056,002 De Sakhnofisky Sept. 29, 1936 2,069,633 Tripp Feb. 2, 1937 2,072,240 Zigler Mar. 2, 1937 2,152,915 Pye Apr. 4, 1939 2,165,637 Little Jul 11, 1939 2,484,950 Jaffe Oct. 18, 1949 2,513,147 Chorpening June 27, 1950 

